Exhaust system for gas turbine engines in aircraft



June "1953 G. OULIANOFF ET AL 2,641,422

EXHAUST SYSTEM FOR GAS TURBINE ENGINESIN AIRCRAFT :F'iled March 8, 1949s Sheets-Sheet 1 fiwmmes 6350265 00 MNOFF' (f A. DAV/J June 9, 1953 G.OULIANOFF ETAL EXHAUST SYSTEM FOR GAS TURBINE ENGINES IN AIRCRAFT FiledMarch 8. 1949 3 Sheets-Sheet 2 DA /5 m June 9, 1953 G. OULIANOFF ETALEXHAUST SYSTEM FOR GAS TURBINE ENGINES IN AIRCRAFT Filed March 8, 1949 3Sheets-Shegt 3 m m m r w GEORGE oULMA/vii" 6.4.0.4176 v bg m. o M

Patented June 9, 1953 EXHAUST SYSTEM FOR GAS TURBINE ENGINES IN AIRCRAFTGeorge Oulianoff, Allestree, Derby, and Christopher Ainsworth Davis,Barrow-on-Soar, near Loughborough, England, assignors to Rolls- RoyceLimited, Derby, England, a British com- Application March 8, 1949,Serial No. 80,124 In Great Britain February 18, 1947 4 Claims. (Cl. 244).This invention relates to exhaust assemblies for aircraftas-turbine-engines. Such an engine normally comprises a compressorsystem, combustion equipment and a turbine system, the exhaust gasesfrom which are directed rearwardly with respect to the direction offiight of the aircraft for propulsion purposes; such reaction propulsionmay constitute sole propulsion means for the aircraft or may be used inconjunction with an airscrew or ducted fan driven by the turbine system.v

The present invention is concerned with problems arising in theinstallation of gas-turbineengines in aircraft and has for an object toprovide an improved exhaust assembly which facilitates installation inan aircraft and enables the structural design of the aircraft to besimplified.

A further object of the invention is to reduce the overall drag involvedin the installation of the engine in the aircraft.

According to the present invention, in an aircraft wing structure havinga main spar, a gasturbine engine mounted in the wing structure forwardlyof said main spar and an exhaust assembly for the engine, there isprovided an exhaust assembly construction having a part which extendsfrom forwards of the main spar to rearwards of the main spar, sai-d partbeing formed by a plurality of exhaust pipe members having their axes ina common plane extending substantially parallel to the direction ofnormal flight, the exhaust pipe members having partcylindrical wallportions joining adjacent partcylindrical wall portions in cuspformations and there being means interconnecting the cusp formationsbetween a pair of exhaust pipe mem bers, and a duct section locatedforwardly of the main spar and said exhaust pipe members, said ductsection having a single inlet connected to receive the exhaust gasesfrom the engine and a plurality of outlets one connected to deliverexhaust gas to each of said exhaust pipe members. The means joining thecusp formations may be a plane separating wall or a series of stays. Areduction of the minimum dimension of the exhaust system is thusobtained whilst by retaining substantially circular-sectioned ducts theweight of the ducts is kept low.

Further, in partly under-slung gas-turbineengine wing-installations, theexhaust assembly the engine is avoided.

of this'invention is advantageous in that local bowing of a main spar toprovide clearance for the exhaust assembly passing below it isunnecessary and at the same time excessive lowering of In other aircraftconstructions, the exhaust assembly may be accommodated readily betweenupper and lower main spars without the latter being shaped to clear theassembly.

As compared with known exhaust systems which have a single circularsectioned exhaust duct or jet-pipe and have a minimum dimensionrepresented by the overall diameter of the duct, an exhaustsystem of theinvention adapted to carry the same through-put of exhaust gases andhaving two or more substantially circularsectioned exhaust ducts has asubstantially reduced minimum dimension represented by the maximumoverall diameter of one of the ducts.

A gas-turbine-engine powered aircraft when fitted with an exhaustassembly arrangement as set forthabove, may have a nacelle which invertical section is of aerofoil or streamline form to accommodate engineand exhaust assembly with the exhaust assembly extending to adjacentthe'trailing edge of the nacelle. In such an arrangement the shape ofthe trailing edge of'th'e nacelle may be made more closely to conform toa true streamline section whilst the design of the aircraft structuremay be simplified and the installation of the gasturbine-engine andnacelle structure is facilitated since more space is available in thehorizontal plane than in the vertical plane for clearance purposes.

There will now be described by Way of example of this invention, someconstructions of exhaust assembly suitable for use with a gas-turbineengine installed in an aircraft wing for reaction propulsion purposes.The description refers to the accompanying drawings in which:

Figure 1 is a diagrammatic view of an aircraft fitted-with an exhaustassembly of this invention,

Figure 2 is a plan view of one construction of exhaust assembly,

Figure 3 is a sectional elevation of the exhaust assembly, the sectionbeing partly on the line 33 of Figure 2, j r

Figure 4 is a view on the outlet end of the ex-v haust assembly, a

Figure 5 is a section through the aircraft wing adjacent a main spar,

Figure 6 illustrates a second construction, and

Figure 7 is a sectional elevation of the exhaust assembly in a wingnacelle.

Referring to the drawings, the engine 9 comprises the turbine IO and islocated in a nacelle II in wing I 2 of an aircraft 8 (Figure 1). Aposition for the wing main spar 20 is indicated in Figure 1.

The nacell ll of which the rearpbrtion is shown in Figure 4, is invertical section of substantially aerofoil or streamline form, and will,as is usual, have an air inlet-atwitsrforward: end.

The turbine I has an annular outlet-borne municating with the primaryexhaust unit l3 which is conveniently of known for'm compr sing an outercasing and ani inner substantially conical fairing between whichfthere'is'"defined an annular exhaust passage which 'merg'es'into a cylindricalpassage at the apex of the conical fairing.

The secondary exhaust assembly-comprises a duct section I 4 which isbolted to the unit '13 which, as will be seen from Figures 1 and 2, hasa circular-sectioned inlet "end 15 to register with segmental outletsI6; it being "arrangedthatthe efiective total areaoftheoutletsldisisubstantially the same as*theareaof'theinleti' l5.'Intermediate the inlet I and outlets" lt' the duct sectionflattensand'widens in a manneftoensurethat-thechange offiow of theexhaust'gase's through it is "efiected smoothly.

The duct section *deiiversto a'pair of 'jet pipe members H whichare'built-up from a numleer-of fianged'sectrons -l1a'-*which are major parts5 of; cylindersthef'j'etmipei members having th'eir axes'parallehandhaving either aplane dividingw'allflb(Figure 3 "01 a7seriesofistaysn (Figure 6) joiningthecus'psZEl formed at? the junctionsof' the "part "cylindrical. section 'I'Ta. Thereby -the"jet=pipe"members ll'f'mate "with the segmental outlets "f8 'beyond"the'""trailing edge' 1-8 ofthe' wing but short of the outletend of thenacelle. Each'jet-p'ipe I 7 is 'fitted at its outlet endw'ith anoz'zlel9'jwhich'proj'ects' slightl'y beyond the trailing "edge 'of the nacellel I.

From the foregoing-description;'ittvill "be appreciated that thediameter of theportionl'la of the-j et-p-ipes H is so chosen'thattheirtotalefie'ctive "area is equivalent to A the eifective "area of a'singlejet-pipe which would,"in aconventional construction," befitte'd to the'outietfronr tlrgex- 'h'a-ust unit l'fiin place 0'ftlieparts Mfi'f'l.

It'will be appreciated moreoverthat since the axes of 'theportions ilaof the jet pipes I "1' lie in a horizontal-plane (as 'vieWedin thedrawing) the overall vertical-dimension is "substantiallydess than thecorresponding"dimensionof a conventional single-jetmipe; althoughtheo'Verall-hori zontal dimension'is somewhat greaterthanthat of theconventional single jet-pipe.

The' arrangement orthe invention has tas oompared .withthei=conventionaliasingle; j eta-pipe 2 are rangement). ,Ithe advantages-that: in wvingiinstallations- (a) Thesnacelle .cansconfornr-moreclosely to a streamline section; :-(b)-The jetepipesare morereadilyaccommodated .in-the region of the rear main spar of the wing.For example where the main spar. is of -fbanjo.: form as illustrated atZI,.the depth of 'thel b-anjoiicantbe reduced; alternatively, "where" theengine is un'dr' slung local bowing of the main,sparinfth'efregionof theengine is unnecessary to permit the exhaust assembly to pass below itand at the same time excessive lowering of the engine is avoided; wherethe wing is formed with upper and lower rear main spars the exhaustassembly can be 5 accommodated between the spars without their beingshaped to clear the assembly. (a) A reduction in the minimum dimensionof the exhaust assembly is obtained whilst the weight of the ducts iskept low due to the use of substantially circular-sectioned ducts. f g

Th increa-sedmaximum 1*diniehsioi iof the assembly does not give rise toany disadvantage in ihstallation since the greater width can bereade-ilyiaccommodatedin a wing structure.

:Theuseas'far as possible, of part-circular portions Ha throughout theexhaust assembly has theadvantage-thatthe weight of the assembly iskep-t low i'n respect to the pressure loading to %wh'ich"-th'e' ductsare subjected internally.

"Theinve'ntion is not limited to the use of an exhaust assembly -havingtwo parallel exhaust .Z- ductsgsinc'e if. desired three or more parallelexf haust ducts-may be provided in an exhaust assembly. 1 In theconstruction illustrated, each exhaust duct I! is provided withaseparate propelling nozzle 1'9. It is -contemplatedwhat'in certain casesa single exit nozzle may "be provided; the flow through the ducts-Nbeing unified. by"means "of a duct'section functioning inthe reversem'amtier to the duct' section 1 L Such-an arrangement may be adopted toenable the -exhaust 'duct' to avoid structure of theairframewhichwouldpre ven't-the passage of a continuoussingle-exhaust611013.

claim: 1. In an aircraft wing structurehayingamain spar; a"gasturbineenginemounted irr thewing structure forwardly" ofs'aid' main spararidanex haust assembly 'tfonthe' engine, a con'structicifof saidexhaust assembly having apart -whi'ch ex tends --from forwards oithe-'-main;"spar-to rear wards of the mainspar ;'saiw-partbeingformed by aplurality of exhaust pipe members having their axes in a common plane"extendingsubst-antially parallel to the'directionof normal-flight, theexhaust pipe members "having" part cyiindri- 'carwall-"pbrticns joiningadj acent' part- -cylindrh calwall ortions incusp -formations and th'erebeing" meaiis inter'connecting'the 'cusp formations between a pair ofexhaustpip'e -'members, and a 'duct' section located forwardly of themain spar and said'exhaust pipe members; said -duct section having a'single inlet "connected to receive the exhaust gases 'fromth'e engineand a plurality or outlets "one: connected -to "deliver-exhaust gastoea'ch of said exhaust pipe members.

2LA: construction'"of' '"exhaust"assembly as claimed in claim I whereinthe means *joining the cuspiorrnations'is'aplane-"separating wall. 3: Aconstruction 'o'f""exhaust" assembly {as claimedin claim 1; wherein themeans 'joining the cusp formations c'omprisesa'seriesofstays.

'4. In "an "aircraft win-g 'structure-lnavinga main spar, a gas-turbine"engine mounted inthe wing structure forwardly of said mainspar; and an exhaust assemblyfor"the"engine-, a construction Of saidexhaustassemblyf'havingthepai't which extends from 'forWardsof-themain'spar to' rear- Wards .of "the" mainsp ar, said part-bi ng formed bytwo exhaustpi'pemembershaving their axes parallel and"-extendingsubstantially iii-' the direc-v tion of'normalflight,"each' exhaust pipemember comprising a wall port-ion-"'w'h ich is the ma impart of acylinder and"joins-the%bther "-Wa1l=='-p0rtion References Cited in thefile of this patent UNITED STATES PATENTS Name Date Schaefer Apr. 9,1929 Number Number 2,103,466 2,280,835 2,420,323 2,441,488 2,488,174

Number Name Date Klemm et a1 Dec. 28, 1937 Lysholm Apr. 28, 1942 Meyeret a1. May 13, 1947 Howell May 11, 1948 Clegern Nov. 15, 1949 FOREIGNPATENTS Country Date France Oct. 2, 1909 Great Britain July.15, 1946Great Britain Sept. 26, 1946 Great Britain Feb. 11, 1947

